AMSTERDAM – There were several explosions at 3.00 am this morning at the high security courtroom where the trial of "top criminal" Willem Holleeder is set to start today. There has been substantial damage to the building, police report.

The spokesperson says that several windows were broken. There were no injuries. The police are doing everything to ensure that the trial can begin today.

A spokesperson for the national office of the public prosecution department says that the trial will indeed take place. The Haarlem court, which is trying the case against Holleeder and fellow suspects, was not available for comment.

The lawyer of "top criminal" Willem Holleeder said on Sunday that he will be calling two anonymous witnesses during the trial against his client. They will testify that real estate magnate Willem Endstra, whose murder Holleeder is suspected of having master-minded, was himself behind a failed murder attack and even blackmailed a business partner.

Holleeder''s attorney Jan-Hein Kuijpers said he could not disclose anything more about the matter. "That could compromise the anonymity of the sources."

Willem Holleeder and his accomplices are suspected of systematically blackmailing some four wealthy businessmen, mainly active in real estate.

One of them was reportedly Willem Endstra. Holleeder is accused of leading a number of criminal organisations: groups whose composition changed frequently but who were all out to extort millions from their victims.

Violence, threats and intimidation were standard tools in these groups'' arsenal. The suspects were arrested in January 2006. Five of them, including Holleeder, are still being held in custody.